Electrical condenser construction



Aug. l, 1939. R. E. CRAMER 2,157,877

ELECTRICAL CONDENSER CQNSTRUCTION FiledNov. ze, 1935 INVENTOR 2f JQ@ ATTORNEY Patented Aug. l, 1939 UNITED STATES PAK/Tuur orric Russeli E. Gramer, Audubon, N. J., assigner to Radio Condenser Company, Camden, N. J.

Application November 26,1935, Seria No. 51,593.

6 Claims.

'this invention relates to the general construction of an electrical condenser such as is used in tunable circuits in radio receiving sets, and has to rio with improvements in variousdetails entering 5 into the construction and operation of the condenser.

is one oi the objects oi my invention to provide au improved form of frame which supports the stator and rotor groups of plates.

,o Another object oi my invention is to provide a simpler, cheaper and improved form of attachment of the stator group of plates to the frame.

A still further object oi my invention is to provice an improved, method ci attaching a trimmer gelate to the condenser unit.

These and other objects will he clear to one siiiled in this art, on reading the attached specihcaion, taken n connection with the drawing,

www g3 Figure i is a sice eievation, on an enlarged scaie, of a. three-gang condenser embodying my improvements, the trimmer plate being removed. Figure 2 is a bottom View of the gang condenser shown in Figure l.

.ii/Figure 3 is a section on the line oi Figure l. Figure 4 is a section on the line of Figure 2. Figure .5 is a section on the line --ti oi Figure l. Figure 6 is a section on the line oi Figure 2. Figure '7 is a perspective View of the terminal Q strip used for supporting the stator group of plates to the insulator carried by the frame.

in the various vier/s, ail ci which are on an eniargeti scale, wherein like numbers refer to corresponding parte, the frame ofthe gang con- 5 denser inciucies ttvo end plates i and i? which are preerabiy punched integral with the cross bars 3 and ll, and then leent or formed in a peculiar manner as shown in. Figures 1, 2, 3, i and 6. As shown in these iigures, the bottom cross bars i p and have their sides i and 6 formed so as to provide a channei-shaped bar, and at the points i, oiosel,7 adjacent the plane or" the end plates i and 2, the metal of the frame is curved as indicated by the lines and 9, so that the channel 5 edges 5 and @i ci the bars 3 and i are continued into the upturned edges i9, thereby providing a tremendous stiftening means closely adjacent the line of bend of the end plates i and 2.

l have found that this construction gives a frame which is very much stiier than a frame in which the end plates I and 2 are made separate from the bottom and sides and riveted thereto as shown in S. S. Cramer Patent 1,890,719, issued April 14, 1931; or much stiffer than a frame in which the end plates are integral with the bottom (Ci. 17E-411.5)

portion and cent upwardly therefrom., outu ting out the greater part oi the botten of the condenser, leaving only the channel members 3 and ll, the minimum capacity ci the condenser is lowered and the entire trame structme mas terially lightened, yet great rigidity is obtained by forming the channel merrhers and emi the end plates i and. as descritas As, shown in Figures i anti 2, the end i and. 2 carry a rotor`1 "t it which is suni0 ported therein in any sanefactory the use of an anti-*friction t2 plate t, and a hail-thrust in theV drawing, no has been made to i5 shotv .ali of the indiviciiiai i iates the rotors and stators oi various units. However,` one rotor plate t@ f indicated. Between each ce is positioned a shield his. beine,r riveted as at t@ 'to ia and 3, and. also stvecigeti i7 to the cross nieta! trahie member t@ which is also riveted or stvedgerl at to the end plates t c.--

The stator group of plates each is 25 carried by insuiators rl f it? in any satisiactory manner Each insuiator 2@ extentie @c sideraoie distance below the and on the lewe" terminal strip tv adapted he in sides of the 2Q, t over the ree-r iace or' inst ing the terminal strip n sulator. tending invfarily tow proximity with the tie 2SA@ *zich stator plates are connected. union between the fingers and the f. cie icy soicier- 4.0 ing, as disclosed in Ptusseii T ramer application Serial No. 717,859, i. ch 25%, i934. The terminal 22 also has a 1re-roi g i3 to "which the connecting Wire is fas sci any' satisfactory manner, as hy soif .t 45

The insulator has a tapped hole 2t?, considerahly smaller in diameter than the holte 3@ in the terminal to receive an adjusting screw 3l used for adjusting,r a trimmer plate 32 which is fastened dirtly to the metai trarne bar i3 50 by the rivets Zi. It viii he noted from the section in Figure 3, that an insulator, such as a piece of mica 33, is positioned nett-veen the lower portion of the trimmer piate 52 and the tace of the terminal plate 22 to prevent the screw 3l from 55 teer group, there te t5, the saine 2@ .oy rivets 2t.

a conn te. D

ers 2h exit into ciose yto the closely mounted trimmer plates;

forcing the plate 32 into contact with the terminal strip 22, and thereby prevents short-circuiting of the condenser unit.

This method of mounting the trimmer plate places the trimmer plate at ground potential, thereby eliminating the necessity yof extending the shield plates l5 beyond the opposite sides of the frame, as has been done in the past, to prevent interaction between the various units,|due 4This construction also eliminates the use of aBakelite bushing whichv must be used in connection with the adjusting screw when the trimmer plates are mounted in the usual way, as generally set forth in Patent 1,800,719 heretofore referred to.

It may be mentioned in passing that the cross frame members 3 and 4 are provided with bosses l34` formed by forcing the metal outwardly as shown in Figure 1, and these bosses may be tapped to receive screws for holding the condenser on a suitable mounting plate.

The construction heretofore described f provides a very rigid and non-warping frame, even though the same is made very light by punching out a large portion of the central part thereof. By bending over the edges of the cross frame members 3 and '4 to form a channel, and continuing these bent-over edges into the ared form at 8 and 9, as has been described, while the end platesl and 2 are being 'formed into position, provides' an extremely rigid frame, and this rigidity aids in maintaining the spaced relation between the rotor and stator plates after they have been assembled, as defined in the Russell E. Cramer application previously referred to.

What I claim is:

1. For a variable electrical condenser having a rotor with shaft, and stator plates; a non-warping yframe comprising a stamping having an integral upturned plate at each end providing bearing supports for the rotor shaft and a plurality of spaced bottom cross members having their edges formed over to provide a frame member having a cross section similar to a channel, the material at the opposite ends of said channel-shaped member, closely adjacent the end plates, being flared away from the member and these ared portions turned inwardly toward their respective endvplates, and a frame bar on each side of the condenser extending between the end plates and anchored thereto, and acting at least in part as a support for the stator plates.

2. For a variable electrical condenser having a rotor with shaft, and stator plates; a nonwarping frame comprising a stamping having a large part of the central portion entirely removed leaving on opposite sides thereof frame members with end portions extending therefrom, said frame members having their edges turned inwardly to form channels which terminate in flared ribbed portions closely adjacent said end portions, said end portions having a bend closely adjacent said flared portions in the same direction to form end plate supports for the rotor shaft, and a frame bar on each side of the condenser extending between the end plates and anchored thereto, and acting at least in part as a support for the stator plates.

3. In an electrical condenser having a frame, rotor and stator plates, the latter of which are fastened to tie bars for attachment to insulators plate having holes concentrically arranged but the hole in the terminal plate being materially larger in diameter than the hole in 'the insulator, the latter hole being tapped, a trimmer plate fastened directly to said bar member and extending downwardly over said terminal plate but prevented from contacting therewith by an insulator, and an adjusting screw passing through the trimmer plate and into the tapped hole in the stator support insulator.

4. In an electrical condenser having a frame,

rotor and stator plates, the latter of which are fastened to tie bars for attachment to insulators carried by metallic bar frame members on oppo' site sides thereof and spaced from the bottom of the frame; said attachment comprising a terminal plate fastened to the lower portion of each insulator, and a trimmer plate fastened on at least one side of the condenser directly to the frame bar on that side and extending downwardly over said terminal plate, with means for adjusting its relation thereto, and an insulator positioned between the terminal plate and the trimmer plate, the terminal plate having fingers to which the stator tiebars are fastened, and means for making connection to the terminal plate.

5. In an electrical condenser having`a frame, rotor and stator plates, the latter of which are fastened to tie bars for attachment to insulators carried by metallic bar frame members on opposite sides thereof; said attachment comprising a terminal plate lying across the outer face of each insulator and spaced from said bar frame members, said plate having lugs clinched around parts of the insulator and also having fingers extending inwardly toward the stator tie bars for attachment thereto, and a further part to which al conductor may be attached, said insulator and terminal plate having holes concentrically arranged but the hole in the termin-al plate being materially larger in diameter than the hole in the insulator, the latter hole being tapped, a trimmer plate fastened directly to said bar member and extending over said terminal plate, and an adjusting screw passing through the trimmer plate and into the tapped hole inthe stator support insulator.

6. In an electrical condenser having a frame, rotor and stator plates, the latter of which are fastened to tie bars for attachment to insulators carried by metallic bar frame members on opposite sides thereof; saidv attachment comprising a terminal plate fastened to a portion of each insulator and a trimmer plate fastened on at least one side of the condenser directly to the frame bar on that side and extending over said terminal plate, with means for adjusting its relation thereto, the terminal plate having fingers to which the stator tie bars are fastened, and means for making connection to the terminal plate.

RUSSELL E. CRAMER. 

